Controller Tests for Molten Salt Parabolic Trough Systems with Loop-Wise Control Valves

Concentrated Solar Power systems are used to generate thermal and electrical energy from solar radiation. Molten salt as a heat transfer medium offers the possibility of a higher temperature in the solar field and at the same time the use of direct energy storage. The Évora Molten Salt Platform is a research platform to study molten salt in the solar field on a pre-commercial scale [1]. The use of molten salt requires to adapt control concepts used in thermal oil fields since the temperature rise over the loop and the loop length are different from those of thermal oil. One approach is to use automatic valves in each loop to individually control the temperature at the outlet of each loop. This paper presents controller tests performed at the HPS2 molten salt loop of the Évora Molten Salt Platform for normal operation and start-up mode that provide the basis for an individual loop flow control strategy.